Systemic disease and the eye Flashcards
(54 cards)
What is myotonic dystrophy?
Group of inherited conditions that show muscle weakness and myotonia (inability to relax after muscle contraction)
What are the 2 main types of myotonic dystrophy?
Classic dystrophia myotonica 1 (DM1)
Type 2 myotonic dystrophy (DM2)
What mutation causes classic dystrophia myotonica 1 (DM1)?
AD mutation in dystrophia myotonica protein kinase gene DMPK
What is type 2 myotonic dystrophy?
A milder version caused by a different mutation (abnormally expanded section in ZNF9 gene)
How does myotonic dystrophy present?
- Muscle wasting and weakness
- Mournful facial expression (facial wasting, loose jaw)
- Slurred speech (tongue/pharyngeal muscles involved)
- Frontal baldness in males
- In OSCE, would shake patients hand to show difficulty in releasing grip
What are some common ocular manifestations of myotonic dystrophy?
- Early onset cataract
- Pathognomonic: stellate posterior cortical catact
- Also ‘Christmas Tree’ (polychromatic) cataract (can also be age-related finding)
- Ptosis
- Hypermetrophia
What is shown?
Stellate posterior cortical cataract
What is shown?
Christmas tree (Polychromatic) cataract
What are some uncommon ocular manifestations of myotonic dystrophy?
- Mild opthalmoplegia
- Pupillary light-near dissociation
- Pigmentary retinopathy
- Optic atrophy
What are the 2 main ocular features of neurofibromatosis?
Optic glioma
≥ 2 Lisch nodules
What is optic glioma?
- Slow growing tumour of the optic nerve which causes fusiform enlargement, resulting in globe proptosis and an afferent pupillary defect
- Optic nerve may be swollen (or atrophic later)
- 30% have associated NF1
What is shown?
Optic glioma
What are Lisch nodules?
- Bilateral yellow or brown dome-shaped nodules
- Develop during 2nd-3rd decades, eventually present in 95% of cases
What is shown?
Lisch nodules
What are some non-ocular features of neurofibromatosis type 1?
- ≳6 cafe-au-lait macules
- ≳2 neurofibromas of any type, or one plexiform neurofibroma
- Axillary or inguinal freckling
- Distinctive osseous lesion e.g. sphenoid dysplasia or thinning of long bone cortex, with or without pseudoarthrosis
- First degree relative with NF1
What is thyroid eye disease?
Autoimmune disease caused by the activation of orbital fibroblasts by autoantibodies directed against thyroid receptors
What are some conditions that can cause thyroid eye disease?
Grave’s disease (90%)
Hypothyroidism (10%)
Describe the pathophysiology of thyroid eye disease
- Orbital fibroblasts activated by Graves’ disease-related autoantibodies, leading to an inflammatory response
- This results in enlargement of extra-ocular muscles, fatty and connective tissue volume
What are the 5 stages of thyroid eye disease?
- Soft tissue involvement
- Lid retraction
- Proptosis
- Optic neuropathy
- Restrictive myopathy (inflammation and fibrosis)
What are some symptoms of soft tissue involvement in thyroid eye disease?
Grittiness
Photophobia
Lacrimation
What are some signs of soft tissue involvement in thyroid eye disease?
Hyperaemia
Chemosis
Periorbital swelling
What is a possible complication of proptosis?
Could lead to exposure keratopathy → corneal ulceration
What is shown?
Thyroid eye disease
What are some management options in thyroid eye disease?
- Thyroid dysfunction control
- Stop smoking
- Selenium supplementation
- Lubricants
- Systemic steroids
- Radiotherapy
- Monoclonal antibody treatment
- Surgical decompression
- Eye muscle surgery
- Lid surgery
